High colour quality luminaire

ABSTRACT

A colour tunable lighting module is described which includes at least three solid state lighting emitters (such as light emitting diodes) and at least two wavelength converting elements (such as phosphors). The three solid state lighting emitters are formed of the same semiconductor material system and the light generated by them has dominant wavelengths in the blue-green-orange range of the optical spectrum. The two wavelengths converters are used re-emit some of the light from two of the emitters in broader spectra having longer dominant wavelengths, while the third emitter is selected to emit light at a wavelength between the dominant wavelengths of the light from the two emitters and the two converters. A control system may be employed to monitor and control the module and the lighting module can be optimised for tunable high colour quality white light applications.

FIELD OF THE INVENTION

The present invention relates to a colour tunable lighting module whichincludes three or more solid state lighting emitters (such as lightemitting diodes) and two or more wavelength converting elements (such asphosphors). In particular the lighting module is optimised for tunablehigh colour quality white light applications.

BACKGROUND

Light emitting devices or diodes (LEDs) are based on a forward biasedp-n semiconductor junction. LEDs have recently reached high brightnesslevels that have allowed them to enter into new solid state lightingapplications as well as replacements for high brightness light sourcessuch as light engines for projectors and automotive car headlights.These markets have also been enabled by the economical gains achievedthrough the high efficiencies of LEDs, as well as reliability, longlifetime and environmental benefits. These gains have been partlyachieved by use of LEDs that are capable of being driven at highcurrents and hence produce high luminous outputs while still maintaininghigh wall plug efficiencies.

Solid state lighting applications require that LEDs exceed efficienciescurrently achievable by incandescent and fluorescent lightingtechnologies. Currently, one of the preferred routes for the generationof White light from an LED module is by use of a single colour LED (suchas a blue LED) and a wavelength converting element (such as a yellowphosphor). Wavelength converting elements (WCE) typically comprise of ayellow phosphor mixed in an encapsulant and dispensed at the correctcomposition on top of a blue LED chip to generate a white colour of thedesired colour temperature. By modifying the fill fraction compositionor % weight the white light colour may be tuned. The ability to providewhite light across a large chromaticity space is advantageous fordifferent lighting applications. However, due to manufacturinginaccuracies associated with variation in LED emission wavelength, LEDemission bandwidth, variation in WCE % weight and WCE compositiondifferent LED modules will exhibit white light emission characteristicswith different chromaticity values. This is undesirable as sorting andbinning of LED modules post manufacture is required. Additionally, thespectrum of the total emitted light (TEL) arising from Blue and yellowemission typically provides a low to medium colour rendering index (CRI)in the range 60-80.

U.S. Pat. No. 6,788,011 describes the mixing of Red, 102, Green, 103,and Blue, 104, primary colour semiconductor LEDs to provide white colourlight as shown in FIG. 1 a. In order to achieve the desired lightintensity as well as the colour chromaticity on a CIE diagram (astandard colour space created by the International Commision onIllumination), a control system is programmed with predefined LED driverpower values for each individual LED colour. The light emission spectraintensity, 106, plotted against wavelength (as shown along 105) for eachLED namely the Red LED, 109, Green, 108 and Blue, 107 are shown on theinsert in FIG. 1 a. The individual LEDs are assembled in a housing orboard, 101. This LED lighting system suffers from several drawbacks, asdetailed below.

Firstly, the LED lighting system suffers from poor Colour RenderingIndex (CRI) typically around 27-30 because of the individual narrow Red,Green and Blue wavelengths (approximately 10-25 nm bandwidth wavelengthemission) providing poor representation of the complete visible spectrumof light, which is typically experienced from incandescent bulbillumination or blackbody radiation, 120, as shown in the insert in FIG.1 a. As a reference, the CRI for a blackbody radiation is 100 and thevalue ranging between 0 and 100 defines how accurately light willportray colours relative to a blackbody source at the same nominalcolour temperature.

Secondly, due to the different LED semiconductor material systemsrequired to generate Red (typically InGaAlP) and Blue or Green (InGaAlN)wavelengths, the relative light intensity, voltages, lifetime andjunction temperature may dramatically vary from one LED to another. Itis also important to note that when the LED junction temperature isincreased, the relative light output from a light emitting devicecomprising of a InGaAlP material system is degraded at a greater ratethan a light emitting device comprising of a InGaN material system andhence all these factors will adversely affect the overall lightintensity, colour chromaticity point and colour quality with lifetimeand temperature giving rise to an LED lighting system that is unstableand not useable. This is typically very difficult to monitor without theaddition of feedback control systems.

In U.S. Pat. No. 7,213,940B1 another colour control system is proposed,whereby a first semiconductor LED with a first lumiphor is provided togenerate white light. In order to improve the CRI, a secondsemiconductor LED having a different emission wavelength is introducedinto the optical mixing. This system provides much improved ColourRendering Index (CRI) of around 80-92 due to the broader emissionachieved by the first LED and lumiphor. The introduction of the secondsemiconductor LED with Red emission wavelengths has a limited emissionbandwidth and hence is restricted in the amount that the CRI can beincreased. Secondly, the external efficiency of state of the artcommercial red emitting semiconductor materials such as InGaAlP istypically 30%, which is much lower than that of GaN based blue emittingsemiconductor LED systems (state of the art commercial LED externalefficiency at 45%). Additionally, similar lifetime degradation problemscompared to LED lighting devices in U.S. Pat. No. 6,788,011 are alsoexperienced with the second semiconductor degrading at a different rateto the first LED.

In published U.S. Patent Application No. 2008/0048193 A1 a white LEDmodule including a further circuit board is described. The LED modulecross sectional schematic is shown in FIG. 1 c. In one example of theinvention a Green semiconductor LED, 103 and a Blue semiconductor LED,104 are placed on circuit board 101. A Red phosphor, 112, is disposedover 103 and 104 to provide a total emitted white light intensity, 106,against wavelength 105. The total emitted white light has a broad redphosphor emission, 109, and narrow blue, 107, as well as a narrow greenemission, 108, from the semiconductor LED die. The white light generatedfrom the LED module suffers from a poor CRI (expected to beapproximately 50-60) due to the narrow light emissions in the Blue andGreen wavelength regions. Additionally, the intensity of the Greenlight, 113, is dramatically attenuated, 108. The total green lightinitially emitted from the LED die 103 is shown as a dotted line, whilefollowing the propagation through the Red phosphor 112 the finaltransmitted green light is shown as the solid line 108. The attenuatedgreen light dramatically affects the total efficiency of the LED module.It is important to note that this applies across all wavelengths and notspecifically for Red phosphors only.

As will be appreciated by those skilled in the art, there is currently aneed for a LED module that combines the known benefits of low cost LEDmodules with the functionality of tunable colour chromaticity. It wouldbe desirable to provide a module having uniform chromaticity properties,and which also displays good CRI and stable light intensity with a longlifetime.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, a light emittingmodule comprises a first light emitting device (LED) package, a secondLED package and a third LED package, the total light emitted by themodule comprising light emitted by the first, second and third lightemitting packages, wherein:

-   -   the first LED package comprises a first semiconductor LED and a        first wavelength converting element, wherein when activated the        first semiconductor generates light comprising a first dominant        wavelength λ₁;    -   the second LED package comprises a second semiconductor LED and        a second wavelength converting element, wherein when activated        the second semiconductor generates light comprising a second        dominant wavelength λ₂; and,    -   the third LED package comprises a third semiconductor LED which,        when activated, generates light comprising a third dominant        wavelength λ₃,    -   wherein:    -   the first, the second and the third semiconductor LED comprise        the same semiconductor material system;    -   at least a portion of the light generated by the first        semiconductor LED is incident on the first wavelength converting        element and is re-emitted with a first converted optical        spectrum comprising a first dominant converted wavelength λ_(C1)        such that λ₁<λ_(C1);    -   at least a portion of the light generated by the second        semiconductor LED is incident on the second wavelength        converting element and is re-emitted with a second converted        optical spectrum comprising a second dominant converted        wavelength λ_(C2) such that λ₂<λ_(C2), wherein the second        converted optical spectrum is different than the first converted        optical spectrum and λ_(c1)≦λ_(C2);    -   the colour chromaticity of light emitted by the first light        emitting package resides in a 1960 CIE Uniform Colour Space        bounded by a lower isotherm at a correlated colour temperature        of T₁ K and an upper isotherm at a correlated colour temperature        of 200,000 K, wherein an isotherm is defined as the line        perpendicular to the Planckian locus, said light having a        maximum colour chromaticity shift of Δ_(uv)≦±0.10 from the        Planckian locus;    -   the colour chromaticity of light emitted by the second light        emitting package resides in a 1960 CIE Uniform Colour Space        bounded by an upper isotherm at a correlated colour temperature        of T₂ K and a lower isotherm bounded at the correlated colour        temperature of 1,000 K, said light having a maximum colour        chromaticity shift Δ_(uv)≦±0.10 from the Planckian locus,        wherein the correlated colour temperature point of the        intersection of the isotherm T₁ K with the Planckian is greater        than or equal to T₂ K; and,    -   the third dominant wavelength λ₃ of light emitted by the third        light emitting package satisfies the criteria λ₁, λ₂<λ₃<λ_(C1),        λ_(C2) and 485 nm≦λ₃≦595 nm.

In this way, the present invention provides a low cost LED module withwell defined chromaticity properties and the functionality of tunablecolour chromaticity for use in high colour quality white lightapplications.

Preferably, the correlated colour temperatures are defined such that T₁K=5,700 K and T₂ K=3250 K.

Preferably, the total light emitted by the module is pre-defined at acorrelated colour temperature of 4000 K and within a-4 step MacAdamellipse and also a colour rendering index (CRI) of the light is greaterthan or equal to 92.

In some embodiments of a light emitting module of the present inventionit is preferred that:

-   -   the light emitted by the first light emitting package resides at        a first pre-selected correlated colour temperature within a        MacAdam having a colour chromaticity tolerance greater than        within a four step ellipse;    -   the light emitted by the second light emitting package resides        at a second pre-selected correlated colour temperature within a        MacAdam having a colour chromaticity tolerance greater than        within a four step ellipse;    -   the total light emitted by the module resides within a triangle        bounded by the colour chromaticity of the first, second and        third light emitting packages and having a pre-defined        correlated colour temperature within a four step MacAdam ellipse        tolerance; and,    -   the light emitting module has an efficiency parameter and a        colour rendering index (CRI) parameter that is greater than or        equal to the lower of said parameters for the first and second        light emitting packages.

The light emitting module my further include a fourth LED packagecomprising a fourth semiconductor LED which, when activated, generateslight comprising a fourth dominant wavelength λ₄, in the wavelengthrange 405 nm≦λ₄≦475 nm. This provides for even greater flexibility intuning and controlling the overall chromaticity of the light produced.

In some embodiments of a light emitting module of the present inventionit is preferred that:

-   -   the total light emitted by the module is tunable within a        correlated colour temperature range of 3,000 K to 6,500 K and is        defined within a 4 step MacAdam ellipse; and,    -   a colour rendering index (CRI) for the light emitting module        within the correlated colour temperature range of 3,500 K to        6,000 K is greater than or equal to 90.

According to a second aspect of the present invention, a light emittingunit comprises:

-   -   a light emitting module according to the first aspect; and,    -   a memory module affixed proximal to the light emitting module,        wherein pre-determined calibration parameters for the light        emitting module are registered on the memory module.

In this way, pre-determined calibration parameters are readilyaccessible for use the operation of and control of the light emittingmodule.

Preferably, the memory module calibration parameters comprise one ormore selected from a group which includes: first CIE xy coordinates,second CIE xy coordinates, third CIE xy coordinates, fourth CIE xycoordinates, relative light intensity against electrical current, andrelative light intensity against ambient temperature.

According to a third aspect of the present invention, a controlled lightemitting system comprises:

-   -   a light emitting module according to the first aspect or a light        emitting unit according to the second aspect; and,    -   a control system for managing activation properties of at least        one of the first, second, third and fourth light emitting        packages in the light emitting module when activated, the        control system being adapted to manage the activation properties        to achieve a predefined colour chromaticity and CRI for the        total light emitted by the light emitting module.

The provision of a control system allows for tunable control of themodule and the activation of the individual packages and the lighttherefrom.

Preferably, the control system is further adapted to monitor electricaland thermal properties of the light emitting packages in the module andto provide feedback for modifying activation properties of the lightemitting packages in order to achieve the predefined colour chromaticityand CRI for the total light emitted by the light emitting module.

The controlled light emitting system may further comprise a light sensororiented to measure the colour chromaticity properties of at least partof the total light emitted by the light emitting module, the controlsystem being coupled to the light sensor and adapted to provide feedbackto modify activation properties of the light emitting packages toachieve the predefined colour chromaticity and CRI for the total lightemitted by the light emitting module.

The control system may also include an interface for connection toexternal sources and for receiving information from the externalsources.

As will be appreciated, the control system of the present invention canprovide for dynamic feedback and control of the light emitting modulethrough either integral sensor or information received from externalsources.

According to a third aspect of the present invention, there is provideda method of manufacturing the light emitting unit of the second aspector the controlled light emitting system of the third aspect, the methodcomprising the steps of:

-   -   providing the first, second and third light emitting packages        and attaching them to a sub-mount;    -   affixing a colour mixing element proximal to the submount such        that it is at least partially in a propagation path of the total        light emitted by the light emitting module;    -   affixing a memory module proximal to the light emitting module;    -   activating the light emitting module and determining calibration        parameters for the module; and,    -   registering the calibration parameters on the memory module.

When manufacturing the controlled light emitting system of the thirdaspect, it is preferred that the method further comprises the steps of:

-   -   assembling the control system;    -   presetting parameters in the control system; and,    -   interfacing the control system to the light emitting module and        memory module,    -   whereby the control system is adapted to interrogate the memory        module and to employ parameters residing on the memory for        managing the activation properties of at least one of the first,        second, third light emitting package in the light emitting        module to achieve a predefined colour chromaticity and CRI for        the total light emitted by the light emitting module.

The present invention provide the benefits of a low cost light emittingmodule with uniform chromaticity properties in the far field and havinglong and controlled lifetime yet also offering the flexibility andintelligence of tunable colour chromaticity, CRI and intensity either atmanufacture or in the end user lighting application.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the present invention will now be described in detail withreference to the accompanying drawings, in which:

FIG. 1 a (prior art) shows a first example LED module of the prior art;

FIG. 1 b (prior art) shows a second example LED module of the prior art;

FIG. 1 c (prior art) shows a third example LED module of the prior art;

FIG. 1 d (prior art) shows a 1931 CIE Chromaticity Diagram;

FIG. 2 a shows the allowable chromaticity space for the first, secondand third light emitting package of the present invention superimposedon a 1931 CIE Chromaticity diagram;

FIG. 2 b shows a 1960 CIE UCS diagram having the allowable chromaticityspace for the first and second light emitting package;

FIG. 3 a shows a schematic of an example light emitting module of thepresent invention;

FIG. 3 b shows a graph of power spectral density against wavelength ofthe first and second light emitting package;

FIG. 3 c shows a graph of power spectral density against wavelength ofthe first, second and third light emitting package;

FIG. 3 d shows a graph of power spectral density against wavelength ofthe light emitting module of the present invention;

FIG. 4 a shows a schematic of a second example light emitting module ofthe present invention;

FIG. 4 b shows the allowable chromaticity space for the first, second,third and fourth light emitting package of the present inventionsuperimposed on a 1931 CIE Chromaticity diagram.

FIG. 4 c shows a graph of power spectral density against wavelength ofan example of a tunable light emitting module of the present invention;

FIG. 5 a shows a schematic of control system of the present invention;

FIG. 5 b shows a schematic of control system of the present inventionfurther comprising a microprocessor;

FIG. 5 c shows a schematic of an example control system of the presentinvention further comprising a microprocessor and feedback;

FIG. 5 d shows a schematic of a second example control system of thepresent invention further comprising a microprocessor and feedback; and,

FIG. 6 shows a schematic of a preferred method of manufacture.

DETAILED DESCRIPTION

The object of the present invention is to provide a high wall plugefficiency low cost light emitting module and control system having alight output that is flexible and intelligent capable of tuning colourchromaticity, colour rendering index (CRI) and light intensity. In afirst aspect, the high colour quality light source comprises a lightemitting module employing the colour mixing of three or more lightemitting devices having different light emission properties butcomprising the same fundamental semiconductor material system. Theaccurate definition and mixing of the individual light emitting packageswithin the light emitting module enables a rich spectral light emissionoffering high colour quality and CRI. The pre-determined variation inthe activation properties of individual light emitting packages withinthe light emitting module enables control and tunability in the lightemission.

In a second aspect, the high colour quality light source furthercomprises a memory module for storing pre-determined calibrationparameters. In yet a third aspect, the tunable light emitting module mayadditionally incorporate a control system and may be pre-set duringmanufacture or actively defined or monitored in the end user lightingapplication.

The present invention can be incorporated using a light emitting device(LED) of any semiconductor material system such as, but not restrictedto, InGaN, InGaP, InGaAs, InP, or ZnO. However, for illustrativepurposes, and as a preferred example, Blue wavelength InGaNsemiconductor LED having a vertical contact pad structure (sometimestermed vertical LED structure, or thin GaN) will be described in thebulk of the detailed description of the invention.

The light emitting module of the present invention may include a lightemitting package comprising a semiconductor LED, a wavelength convertingelement (WCE) and a sub-mount. The sub-mount is provided to allow forphysical support of the LED and the WCE as well as a method for improvedthermal dissipation to the surroundings of heat generated in the LED andWCE. The package may further include an optical component, such as alens, designed to collect the light emission from the LED and WCE andshape the emission profile.

The wavelength converting element (WCE) may comprise a phosphor, QuantumDots (QDs), nano-phosphors, organic light emitting material or otherelectrically, ionically or optically pumped light emitting material. Thewavelength converting elements may further include surface treatmentsand WCE shell coatings to provide improved light coupling and extractionas well as prolong lifetime and thermal stability. The WCE may furthercomprise optical scatterers or diffusers as well as refractive indexmodifying fillers.

Activation of a light emitting device may comprise electricallyconnecting the light emitting devices using voltage or current drivenpower supplies. The device may be activated using pulsed, switched,sinusoidal, modulated or constant signals. The light emitting devicesare preferably activated using constant current or voltage.

For the purpose of describing the present invention, the colourchromaticity will be defined with reference to a 1931 CIE ChromaticityDiagram using a CIE xyY colour space and also to a 1960 CIE UniformColour Space (UCS) diagram. A standard 1931 CIE Chromaticity colourspace diagram is shown in FIG. 1 d. For simplicity, the luminanceparameter will be removed from the notation and only the chromaticityparameters will be specified by the parameters x,y on the colour space.

In a first embodiment of the invention, a light emitting modulecomprising a combination of first, second and third light emittingpackages is proposed. The first, second and third light emitting packageare selected such that upon activation the light emission issubstantially different. The light emission from the first, second andthird light emitting package is colour mixed to achieve the totalemitted light (TEL). In a preferred embodiment the first light emittingpackage comprises a first semiconductor light emitting device and afirst WCE. The second light package device comprises a secondsemiconductor light emitting device and a second WCE. The third lightemitting package comprises of a third semiconductor light emittingdevice. FIG. 2 a illustrates the colour chromaticity of the lightemission from the three packages on a standard CIE diagram of the typeshown in FIG. 1 d, whilst FIG. 2 b illustrates the allowed colourchromaticity of the light emission from the first and second packages ona 1960 CIE Uniform Colour Space (UCS) diagram.

In the case of the first light emitting package, the colour chromaticityof the light emission resides in a region bounded by the lower isotherm,namely a perpendicular line to the Planckian locus at an arbitrarycorrelated colour temperature (CCT) defined as T₁ K and the upperisotherm bounded at the correlated colour temperature 200,000K, as shownby the dashed boundary 202 in FIG. 2 a. In FIG. 2 b the bounded region206, for the first light emitting package is depicted on a 1960 CIEUniform Colour Space (UCS) diagram 205. In the colour space 205 shown,the allowable light emission region for the first light emitting deviceis again bounded by the isotherms T₁ K CCT and 200,000K CCT, while theextent of the colour chromaticity shift away from the Planckian is up toΔ_(uv)=±0.10.

In a preferred example of the present invention the colour chromaticityof the first light emitting package resides in a region bounded by thelower isotherm, namely a perpendicular line to the Planckian locus atthe correlated colour temperature (CCT) 5,700K and the upper isothermbounded at the correlated colour temperature 200,000K. As shown by thedashed boundary 202 in FIG. 2 a. In FIG. 2 b the bounded region 206, forthe first light emitting package is depicted on a 1960 CIE UniformColour Space (UCS) diagram 205. In the colour space 205 shown, theallowable light emission region for the first light emitting device isagain bounded by the isotherms 5,700K CCT and 200,000K CCT while thewidth of the isotherms are defined as Δ_(uv)=±0.10.

In the case of the second light emitting package the colour chromaticityof the light emission resides in a region bounded by the upper isotherm,namely a perpendicular line to the Planckian locus at an arbitrarycorrelated colour temperature (CCT) defined as T₂ K and the lowerisotherm bounded at the correlated colour temperature 1,000K, as shownby the dashed boundary 203 in FIG. 2 a. In FIG. 2 b, the bounded region207 for the second light emitting device is depicted on a 1960 CIEUniform Colour Space (UCS) diagram 205. In the colour space 205 shown,the allowable light emission region for the first light emitting deviceis again bounded by the isotherms T₂ CCT and 1,000K CCT while the widthof the isotherms are defined as Δ_(uv)=±0.10.

In the present invention, the point of intersection of the upperisotherm boundary at T₁ and the Planckian locus is at a CCT valuegreater than or equal to the point of intersection of the lower isothermboundary T₂ and the Planckian locus as defined by the followinginequality:

T₁≧T₂

In a preferred example of the present invention, the colour chromaticityof the second light emitting package resides in a region bounded by theupper isotherm, namely a perpendicular line to the Planckian locus atthe correlated colour temperature (CCT) 3,250K and the lower isothermbounded at the correlated colour temperature 1,000K, as shown by thedashed boundary 203 in FIG. 2 a. In FIG. 2 b, the bounded region 207 forthe second light emitting device is depicted on a 1960 CIE UniformColour Space (UCS) diagram 205. In the colour space 205 shown, theallowable light emission region for the first light emitting device isagain bounded by the isotherms 3,250K CCT and 1,000K CCT while the widthof the isotherms are defined as Δ_(uv)=±0.10.

The third light emitting package comprises a third semiconductor lightemitting device upon activation having a light emission with a coloursubstantially in the Green to Yellow range. The dominant wavelength ofthe light emission of the third light emitting device is bounded between485 nm and 595 nm. It is an object of the present invention that thethird semiconductor light emitting device comprises a semiconductormaterial system that is identical to the first and second semiconductorlight emitting device. This provides improved intensity and colourstability with life and changes in LED junction temperature.

A schematic depicting an example light emitting module of the presentinvention is shown in FIG. 3 a. The light emitting package of the first,second and third type are depicted as 300, 301 and 302, respectively. Inthe case of packages 300 and 301, there is also included a first andsecond WCE element, namely 304 and 305, respectively. In the case of304, the light emission is predominantly yellowish-green and when colourmixed with the blue emission of the first semiconductor light emittingdevice, 303, the resulting emission, 306, resides within a chromaticityregion bounded by 202 in FIG. 2 a. In the case of the second lightemitting package, 301, with the associated WCE 305, the light emissionis predominantly yellowish-orange and when colour mixed with the blueemission of the first semiconductor light emitting device, 303, theresulting emission, 307, resides within a chromaticity region bounded by203 in FIG. 2 a. In the third light emitting package, 302, the lightemission is predominantly arising from the third semiconductor lightemitting device, 311, with the resulting emission, 308, having a cyan togreen wavelength range that resides within a chromaticity region boundedby 204 in FIG. 2 a.

The light emission from the first, second and third light emittingpackages are allowed to colour mix, 309, to achieve the total emittedlight (TEL), 310. The colour mixing may comprise, but is not limited to,direct colour mixing using one or more of the following techniques, arefractive light guides and lenses, reflective light guides andreflectors, specular light guides and reflectors, diffuse light guidesand reflectors, optical scattering, coherent back scattering, opticaldiffuser sheets, diffractive optical elements (DOE), optical lenses,Fresnel lenses, microlens arrays, back scattering using diffusereflective sheets, diffraction gratings, sub-wavelength optics,integrating sphere, diffuse optical cavities, specular optical cavities,multilayers stacks, optical filters, high reflectivity materials,textured reflectors, multi-faceted reflectors and sub-wavelength optics,such as nano-textured surfaces and bulk materials, as well as photoniccrystal optical elements.

It is important to note that the exact location, device design,manufacturing process and composition of the first, second and thirdlight emitting package and resulting light emitting module of thepresent invention may vary from the schematic shown and should notdetract from the main aspects of the invention. The light emittingpackages may further include additional materials and components such asa sub-mount and optical lens. The sub-mount is designed to aid inphysical attach of the light emitting device and enable improved thermaldissipation between the LED junction and the surrounding. The opticallens may be designed to help light extraction and collect the lightemission from the LED and WCE and re-shape the emission.

The light emission spectrum of the first light emitting package, 334,and the second light emitting package, 330, is shown in FIG. 3 b. Theplot highlights the emission power density, 321, against opticalwavelength 320. It is seen that both the first and second semiconductorlight emitting device emit at a peak in the blue region of thewavelength range, 331, between 400 nm and 460 nm. The WCE emissioncomponent of the light emitting packages constitutes the broaderemission having a dominant wavelength in the yellow region, 332, for thefirst light emitting package, and orange region, 333, for the secondlight emitting package.

It is an object of the present invention that the first and second lightemitting packages do not require accurate pre-selection of thechromaticity point to within a 4-step MacAdam ellipse in order toachieve accurate white CCT along the Planckian. It is an object of thepresent invention that the first and second light emitting packagesreside within a much larger chromaticity domain, as depicted by 202 and203. In a preferred implementation of the present invention, theacceptable tolerance on the first and second light emitting package isgreatly increased and may be greater than a 4-step MacAdam ellipse, butpreferably within a 7-step MacAdam ellipse of the selected CCT. Thisenables much improved colour binning manufacture yield on first andsecond light emitting packages that may be selected for integration intothe light emitting module.

In the present invention the variability in colour chromaticity and CRIis eliminated from the package level manufacturing tolerances andelevated to a light emitting module level concept, whereby defining thecorrect light intensity for each individual first, second and thirdlight emitting package provides the desired CCT within the desiredMacAdam ellipse defining the tolerance of perceived colour. In apreferred embodiment of the invention, the desired CCT value is within a4-step MacAdam ellipse of the target value. The addition of the thirdlight emitting package with a light emission spectrum, 335, as depictedin FIG. 3 c, both enables the ability to shift the CCT as well asimprove colour quality.

The TEL of the resulting light emitting module is bounded by a trianglehaving vertices at the CIExy coordinates of the first, second and thirdlight emitting module, thereby enabling increased flexibility andtunability in the desired colour chromaticity of the module.Additionally, improved colour quality is achieved by adding the spectralcontent of the third light emitting package 335, and overlapping withthe region having minima in the spectrum of the first and second lightemitting devices, 334 and 330. This provides a TEL spectrum, 336, asshown in FIG. 3 d, with increased colour uniformity and colour qualitywhen compared with the individual first, second and third light emittingdevices.

In a preferred embodiment of the present invention, the light emissionfrom the third light emitting package is a shorter wavelength green (orcyan) within the range 485 nm to 520 nm in order to overlap the minimadip residing in the spectrum between the blue wavelength light emissionfrom the semiconductor device and the yellow emission from the phosphor(WCE) of the first and second light emitting package.

By adjusting the intensity of the first, second and third light emittingdevices, the CCT of the light emitting module of the present inventioncan be shifted along the Planckian locus and bounded only by theisotherm perpendicular to the CCT of the first light emitting device andthe isotherm perpendicular to the CCT of the second light emittingdevice, and residing within a narrow well defined 4-step MacAdam ellipsealong the Planckian. In the present example, there exists at least threelight emitting devices having only three possible different lightemission spectra, namely those of the first, second and third lightemitting device type, and a CIE chromaticity point along the Planckianmay be achieved by defining one unique combination of intensities foreach individual first, second and third light emitting device. Thisprovides a fixed efficiency and CRI for the light emitting module of thepresent invention determined only by the underlying efficiency andemission spectrum of the first, second and third light emitting deviceas well as the pre-selected CCT of TEL.

The optical characteristics of the first, second and third lightemitting package for an example light emitting module of the presentinvention are highlighted in Table 1. The correlated colour temperature(CCT) for the third type light emitting package is not defined and hencethe associated CRI is also not defined. The efficiency is measured at apulsed current of 350 mA for all light emitting packages.

TABLE 1 Light emitting CCT CIExy Efficiency package Description (K) CRIx y (lm/W) First type Cool White 6500 K 72 0.314 0.324 92.6 LED Secondtype Warm White 2700 K 82 0.460 0.411 76.2 LED Third type Green LED — —69.3

By employing a pre-defined variation in intensity for each first, secondand third light emitting package, the light emitting module of thepresent invention can achieve a tunable CCT between 3000K and 6000K andwithin a 4 step MacAdam ellipse of the Planckian locus whileadditionally achieving improvements in the CRI of TEL of the lightemitting module.

TABLE 2 Relative intensity of Light Relative Tunable emitting packages(%) CRI CCT First Second Third CIExy improvement (K) type type type x yCRI (%) 3000 8.3 89.9 1.8 0.437 0.404 84 16.7 3500 26.7 70.0 3.3 0.4060.391 84 16.7 4000 44.1 52.9 3.1 0.381 0.377 82 13.9 4500 60.0 38.0 2.00.361 0.364 80 11.1 5000 74.5 25.1 0.4 0.345 0.352 77 7.0

Table 2 illustrates the optical Characteristics for the light emittingmodule of the present invention, and in particular the relativeintensity levels relative to the light intensity at a constant currentof 350 mA required from each channel are highlighted. The relativeincrease or improvement in CRI of the light emitting module over thefirst light package type is also highlighted.

In another aspect of the present invention, the TEL resides on thePlanckian locus and the efficiency of light emitting module is at leasthigher than the lowest of the first and second light emitting packagesand not sensitive to the least efficient light emitting package namelythe semiconductor third module having no WCE. This is contrary toconventional colour changing modules which rely on individual Red, Greenand Blue LED and are limited by the least efficient of the underlyingsingle wavelength semiconductors. This is typically limited by theefficiency of Blue LEDs around 22 lm/W for best in class and Red LEDmodules, around 70 lm/W for best in class. As an example, if an RGBsource delivering a White light with a CCT of approximately 5500K theefficiency would not exceed 57.3 lm/W with a poor CRI of around 30-50.

The efficiency for a light emitting module of the present invention atdifferent CCT points is highlighted in Table 3. Both the efficiency andthe CRI are dramatically improved when compared with RGB light modules.Table 3 also indicates the increase in efficiency across the completeCCT tuning range when compared to the efficiency of the light emittingpackage of the second type. The efficiency of the first light emittingpackage is 92.6 lm/W, second light emitting package is 76 lm/W and 69lm/W for the third light emitting device. The relative improvement inCRI is compared to light emitting package of the first type.

TABLE 3 CIExy Efficiency CCT (K) x y (lm/W) 3000 0.437 0.404 77.0 35000.406 0.391 80.0 4000 0.381 0.377 83.0 4500 0.361 0.364 85.7 5000 0.3450.352 88.3

In yet another implementation of the present invention the lightemitting module may comprise TEL spectral characteristics that aredesigned to provide CIExy coordinates off the Planckian locus. Thedesign criteria enables the TEL of the light emitting module of thepresent invention to possess a chromaticity point residing within thetriangle bounded by the first, second and third light emitting packages.

In another embodiment of the present invention, the light emittingmodule further includes a fourth light emitting package. A schematicdepicting an example light emitting module of the second aspect of thepresent invention is shown in FIG. 4 a. The light emission, 402,generated from the fourth light emitting package 400, is predominantlyarising from the fourth semiconductor light emitting device, 401. Theemission, 402, resides within a chromaticity region bounded by 405 inFIG. 4 b. The upper boundary of the region is defined by the isothermbounded at the correlated colour temperature 200,000K and a secondboundary extending from the Planckian locus at infinite CCT andprojecting towards the boundary of the CIE chromaticity chart at 470 nm.The lower boundaries are defined along the 1931 CIE chromaticity chart.

In one example of this embodiment of the invention, the fourth lightemitting package comprises a single source semiconductor emitter havinga dominant wavelength in the range of blue to cyan with wavelengthsranging from 405 nm to 475 nm. The fourth light emitting package isdesigned to shift the CIExy coordinates of the emission of the firstlight emitting package towards the blue region and further improve thetolerance of acceptable first light emitting packages. This is importantin order to maintain an improved colour tuning range between 3000K and6500K, when the light emission of first light emitting package residesabove the Planckian locus and within region 202. The light emission 306,307, 308 and 402 is colour mixed using the colour mixing element 403 togive rise to the TEL 404. The colour mixing element 403 will employsimilar techniques to those discussed in colour mixing element 309.

An example first light emitting package residing above the Planckianlocus is depicted by point 406 in FIG. 4 b. By introducing the fourthlight emitting package, and in this case having light emission with adominant wavelength of 450 nm, the CIExy coordinate for the first lightemitting package is shifted down along the construction line 407. Theshifted first light emitting package, now residing at CIExy coordinate408, is able to form a much larger colour triangle when combined withthe second and third light emitting packages. This enables a largerwhite colour CCT tuning range for the light emitting module of thepresent invention shifting the tuning range from the original narrow3,000K-3,500K to an improved 3,000K-100,000K.

In one example of this embodiment of the present invention, a highcolour quality, high efficiency device is proposed having a colourtuning range between 3,000K and 6,500K. The optical characteristics ofthe first, second, third and fourth light emitting package arehighlighted in Table 4. The correlated colour temperature (CCT) for thethird and fourth type light emitting package is not defined and hencethe associated CRI is also not defined. The efficiency is measured at apulsed current of 350 mA for all light emitting packages. By employing apre-defined variation in intensity for each first, second, third andfourth light emitting package, the light emitting module of the presentinvention can achieve a tunable CCT between 3000K and 6000K and within a4-step MacAdam ellipse of the Planckian locus while additionallyachieving improvements in the CRI of TEL of the light emitting module.

TABLE 4 Light emitting CCT CIExy Efficiency package Description (K) CRIx y (lm/W) First type Cool White 6500 K 72 0.314 0.324 92.6 LED Secondtype Warm White 2700 K 82 0.460 0.411 76.2 LED Third type Green LED — —69.3 Fourth type Blue LED — — 20.8

Table 5 shows the relative intensity levels required from each channeland highlights the relative improvement (or gain) in CRI as compared tolight emitting package of the first type. By adjusting the intensity ofthe first, second, third and fourth light emitting devices the CCT ofthe light emitting module of the present invention can be shifted alongthe Planckian locus and bounded only by the isotherm perpendicular tothe CCT of the first light emitting device and the isothermperpendicular to the CCT of the second light emitting device and can beoptimised to reside within a narrow well defined 4 step MacAdam ellipsealong the Planckian.

TABLE 5 Tun- Relative intensity of Light able emitting packages (%)Relative CCT First Second Third Fourth CIExy CRI (K) type type type typex y CRI gain (%) 3000 2.26 94.0 3.2 0.5 0.437 0.404 87 20.8 4000 12.075.0 10.3 2.6 0.381 0.377 93 29.2 6000 20.3 62.6 12.6 4.5 0.322 0.333 9025.0

In the present example there exist at least four light emitting deviceshaving only four possible different light emission spectra, namely thoseof the first, second, third and fourth light emitting device type.However, this provides an increased level of flexibility when comparedwith the first embodiment of the present invention having only threepackages, and a single CIE chromaticity point along the Planckian may beachieved by multiple design combinations of the intensities of the firstto fourth light emitting packages. The TEL characteristics are afunction of light intensity of the first to fourth light emittingpackage. By modifying the pre-selected intensities of the four differentlight emitting packages the CCT, CRI and efficiency of the TEL of thelight emitting module of the present invention can all be modifiedindependently. Table 5 highlights an example light emitting modulecomprising high CRI and CCT residing on the Planckian locus and within a4 step MacAdam ellipse.

The TEL of the present module is shown in FIG. 4 c with power spectraldensity in arbitrary units, 411, is plotted against wavelength innanometers, 410. The individual spectral peaks of the third, denoted by413, and fourth light emitting packages, denoted by 412, are alsohighlighted. The light emitting module spectral content is demonstratedfor three different CCT positions namely 3000K denoted by 414, at 4000Kdenoted by 415, and 6000K denoted by 416. The rich full spectral contentof the colour mixed source provides the increased CRI qualities of thelight emitting module while exhibiting minimal reduction in overallefficiency.

In a second aspect of the present invention, the high colour qualitylight source is provided with a memory. The memory may be integratedwithin the light emitting module or reside external to the lightemitting module. One or more of the optical, electrical and thermalcharacteristics of the light emitting module are stored on the memory.The memory may alternatively include pre-determined calibrationparameters defining the current drive conditions for the first to fourthlight emitting packages. These parameters provide the correct currentdrive condition for each light emitting package within the lightemitting module in order to achieve desired CCT and CRI for the TELwithout the need for active feedback.

In an example of this aspect, the memory stores the CIExy coordinatesfor the first, second, third and fourth light emitting packages. In use,the activation of the light emitting module is determined by use ofparameters stored on the memory. Prior to activation, the light emittingmodule driver reads the parameters stored on the memory and defines theintensity or drive characteristics of each individual light emittingpackage and or packages and activates the light emitting module. Thisprovides a method of pre-setting the CCT and CRI of the TEL withouthaving active colour sensing feedback or in-situ application measurementof the TEL of the light emitting module.

During manufacture or calibration, the optical and electricalcharacteristics of the first, second, third and fourth light emittingpackages may be interrogated. The parameters are subsequently stored onthe memory of the light emitting module and may comprise first, second,third or fourth CIExy coordinates, relative light intensity, relativelight intensity against drive current, and relative light intensityagainst changes with ambient temperature.

In another embodiment of the second aspect of the present invention alight emitting module driver (LEMD) capable of activating the lightemitting module is proposed. The LEMD of the present inventioninterrogates the memory to determine the pre-defined activationcharacteristics of each individual light emitting package of the first,second, third and fourth type as well as the desired operating CCT ofthe light emitting module. Subsequently the LEMD activates theindividual first to fourth light emitting packages or packages togenerate the desired CCT and CRI from the light emitting module.

The LEMD may comprise part of the control system of the light emittingmodule and provides a method of managing the activation properties of atleast one light emitting package of the first, second, third or fourthtype in the light emitting module. The control system in conjunctionwith the LEMD is designed to monitor, control and activate the lightemitting module in order to maintain a pre-defined colour chromaticityfor the colour mixed TEL. The active control may be continuous or atpre-defined intervals and allows the light emitting module to deliveraccurate light output, CCT and CRI over varying operating temperatureranges and with operating lifetime.

In a third aspect of the present invention, the high colour qualitylight source is provided with a control system. The control systemprovides a method of managing the activation properties of at least onelight emitting package of the first, second, third or fourth type in thelight emitting module. The control system is designed to achieve apre-defined colour chromaticity for the colour mixed TEL of the lightemitting module. The control system may contain one or more of thefollowing components, microcontroller, light emitting package drivers,memory, and multiple input and output channels. The control system isemployed to provide the semiconductor LEDs with the desired current orvoltage drive intensity to enable a pre-defined colour chromaticity fromthe LED module to be achieved.

Activation properties of the devices may comprise, but are not limitedto, variations in current, voltage, light intensity, modulated signal,pulsed signal, pulse shape, pulse width and duty cycle and frequency.

The control system may further include an interface for connecting thecontrol system to external sources and receiving information from theexternal sources. The control system may further incorporate one or moresensors connected to the control system to provide active feedback. Thesensor may comprise a light intensity sensor, colour sensor or atemperature sensor.

The colour sensor may provide information on at least a portion of oneor more of the light emitting packages in the light emitting module. Theinformation may comprise of the light intensity, colour quality (or CRI)and colour chromaticity point of the TEL. The optical colour sensor mayalso analyse a component of the spectral content of the TEL using anarray of photodiodes coupled to colour filters or gratings, CCD array,photodetector, bandpass filters or a spectrometer.

An example of a simple control system is shown in FIG. 5 a. The controlsystem may comprise of an array of LED drivers for each of the firstlight emitting package 300, the second light emitting package 301 andthe third light emitting package 302, each having individual componentsthat may be modified (by means of tuning or trimming a characteristicsuch as resistance or capacitance), 505, to enable each driver togenerate a different power output. One example method of pre-setting thecolour chromaticity of the LED module is by use of active laser resistortrimming while monitoring of the light output characteristics of the LEDmodule. A trimming resistor is connected to the feedback circuit of eachfirst, 501, second, 502 and third 503 LED drivers, allowing individualcontrol of the intensity of each light emitting package within the lightemitting module.

In another preferred example of pre-setting the colour chromaticity, amicrocontroller, 511, is employed (as shown in FIG. 6 b) to control thedimming input, 510, of the LED drivers of each first to third lightemitting package. Instead of active laser trimming of the resistor themicrocontroller is programmed to include the exact dimming controlsignal to achieve the correct LED power intensity. An interface, 512,for factory pre-setting may also be included. In an alternative aspectof the example, the interface may communicate with the memory, 513, thatcontains the factory pre-set light emitting module parameters.

In another embodiment of the controlled LED module system, the controlsystem may also include a feedback loop. The feedback signal is achievedby use of an optical colour sensor as shown in FIG. 5 c. A percentage ofthe total emitted light is allowed to incident the colour sensor, 521.The signal is fed back, 522, into the controller, 511. This data isprocessed with pre-calibrated algorithms embedded in the controller orthe memory allowing the LED module to be adjusted for any deviations ordrifts in colour chromaticity. The dimming lines of the LED drivers, 510are accordingly adjusted by the controller. An interface, 520, is alsoprovided for factory calibration algorithm downloads.

In other embodiments of this aspect of the invention, the feedbacksignal is indirectly determined from secondary sensors. This is achievedby use of a temperature, voltage and current sensor as shown in FIG. 5d. These sensors monitor the individual light emitting packages forchanges in operating temperature, 535, voltage, 533, and current, 534,across the lifetime and compare with the parameter database stored onthe controller or the external memory, 513.

The temperature sensor may be externally attached to the electricalboard housing the light emitting module. The temperature sensor may bein physical contact with the light emitting module but may also beindirectly linked through a thermal interface linking the light emittingmodule and the temperature sensor, whereby a direct correlation betweenthe junction temperature of the LEDs within the light emitting moduleand the temperature sensor can be assumed. This feature of the presentinvention can only be achieved due to the use of identical LED die ofthe same semiconductor material system, namely Gallium Nitride in thepresent example. During operation, the optical, thermal and electricalcharacteristics are continually monitored in the microcontroller and anydrifts are automatically determined for each first to fourth lightemitting package. The drifts are determined by comparison to referencedatabases stored in the memory, 513, or the microcontroller, 511. Theelectrical current for individual first to fourth light emitting packageis adjusted using dimming, 510, to indirectly correct the colourchromaticity of the total emitted light. The interface, 536, is alsoprovided for factory calibration algorithms and colour controls.

In a fourth aspect of the present invention a method of manufacture ofthe present light emitting module and control system is proposed, asdepicted in the schematic diagram of FIG. 6.

The first light emitting package is attached to a submount as depictedin 601. Subsequently the second, 602, and third light emitting package,603, is additionally attached to the same submount. The sub-mount mayincorporate thermal dissipation elements for efficient heat managementof the LED devices within the light emitting module. The submountfurther comprises electrical tracking to provide means of activating thelight emitting packages.

A colour mixing element, 605, is attached proximal to the submount andthe light emitting module. This is designed to efficiently homogenisethe TEL to achieve a uniform colour against emission angle. This maycomprise a diffuse reflector cup surrounding all the light emittingpackages. The colour mixing element may also incorporate diffusetransmissive optics in the forward propagating path of the TEL.

The module is activated in order to characterise and derive calibrationparameters, 606. Light emitting packages of the same type namely first,second, third or fourth are activated and the light intensity, emissionspectrum and CIExy coordinates are registered.

If the light emitting module is to be pre-set and comprise of a fixedCCT a memory module is integrated incorporating the calibrationcharacteristics of the unique light emitted and the desired CCToperating point of the module, 607. Alternatively, if a tunable lightemitting module is to be defined a memory module is integrated into thelight emitting module having only the calibration characteristics of theindividual light emitting packages, 608. This constitutes a completelight emitting module.

The control system, drive electronics and sensors are subsequentlyassembled and electrically attached to the light emitting module 609.Any preset parameters are downloaded into the control unit via theinterface, 610. The LED module is subsequently activated and the lightoutput is monitored according to the control system protocol in order todeliver the desired CCT or CIExy coordinate, CRI and light intensity.

1. A light emitting module comprising a first light emitting device(LED) package, a second LED package and a third LED package, the totallight emitted by the module comprising light emitted by the first,second and third light emitting packages, wherein: the first LED packagecomprises a first semiconductor LED and a first wavelength convertingelement, wherein when activated the first semiconductor generates lightcomprising a first dominant wavelength λ₁; the second LED packagecomprises a second semiconductor LED and a second wavelength convertingelement, wherein when activated the second semiconductor generates lightcomprising a second dominant wavelength λ₂; and, the third LED packagecomprises a third semiconductor LED which, when activated, generateslight comprising a third dominant wavelength λ₃, wherein: the first, thesecond and the third semiconductor LED comprise the same semiconductormaterial system; at least a portion of the light generated by the firstsemiconductor LED is incident on the first wavelength converting elementand is re-emitted with a first converted optical spectrum comprising afirst dominant converted wavelength λ_(C1) such that λ₁<λ_(C1); at leasta portion of the light generated by the second semiconductor LED isincident on the second wavelength converting element and is re-emittedwith a second converted optical spectrum comprising a second dominantconverted wavelength λ_(C2) such that λ₂<λ_(C2), wherein the secondconverted optical spectrum is different than the first converted opticalspectrum and λ_(C1)≦λ_(C2); the colour chromaticity of light emitted bythe first light emitting package resides in a 1960 CIE Uniform ColourSpace bounded by a lower isotherm at a correlated colour temperature ofT₁ K and an upper isotherm at a correlated colour temperature of 200,000K, wherein an isotherm is defined as the line perpendicular to thePlanckian locus, said light having a maximum colour chromaticity shiftof Δ_(uv)≦±0.10 from the Planckian locus; the colour chromaticity oflight emitted by the second light emitting package resides in a 1960 CIEUniform Colour Space bounded by an upper isotherm at a correlated colourtemperature of T₂ K and a lower isotherm bounded at the correlatedcolour temperature of 1,000 K, said light having a maximum colourchromaticity shift Δ_(uv)≦±0.10 from the Planckian locus, wherein thecorrelated colour temperature point of the intersection of the isothermT₁ K with the Planckian is greater than or equal to T₂ K; and, the thirddominant wavelength Δ₃ of light emitted by the third light emittingpackage satisfies the criteria λ₁, λ₂<λ₃<λ_(C1), λ_(C2) and 485nm≦λ₃≦595 nm.
 2. A light emitting module according to claim 1, whereincorrelated colour temperature T₁ K=5,700 K and correlated colourtemperature T₂ K=3250K.
 3. A light emitting module according to claim 1,wherein the total light emitted by the module is pre-defined at acorrelated colour temperature of 4000K and within a 4-step MacAdamellipse and wherein a colour rendering index (CRI) of the light isgreater than or equal to
 92. 4. A light emitting module according toclaim 1, further including a fourth LED package comprising a fourthsemiconductor LED which, when activated, generates light comprising afourth dominant wavelength λ₄, in the wavelength range 405 nm≦λ₄≦475 nm.5. A light emitting module according to claim 1, wherein the lightemitted by the first light emitting package resides at a firstpre-selected correlated colour temperature within a MacAdam having acolour chromaticity tolerance greater than within a four step ellipse;the light emitted by the second light emitting package resides at asecond pre-selected correlated colour temperature within a MacAdamhaving a colour chromaticity tolerance greater than within a four stepellipse; the total light emitted by the module resides within a trianglebounded by the colour chromaticity of the first, second and third lightemitting packages and having a pre-defined correlated colour temperaturewithin a four step MacAdam ellipse tolerance; and, the light emittingmodule has an efficiency parameter and a colour rendering index (CRI)parameter that is greater than or equal to the lower of said parametersfor the first and second light emitting packages.
 6. A light emittingmodule according to claim 1, wherein: the total light emitted by themodule is tunable within a correlated colour temperature range of 3,000K to 6,500 K and is defined within a 4 step MacAdam ellipse; and, acolour rendering index (CRI) for the light emitting module within thecorrelated colour temperature range of 3,500K to 6,000K is greater thanor equal to
 90. 7. A light emitting unit comprising: a light emittingmodule according to claim 1; and, a memory module affixed proximal tothe light emitting module, wherein pre-determined calibration parametersfor the light emitting module are registered on the memory module.
 8. Alight emitting unit according to claim 7, wherein the memory modulecalibration parameters comprise one or more selected from a group whichincludes: first CIE xy coordinates, second CIE xy coordinates, third CIExy coordinates, fourth CIE xy coordinates, relative light intensityagainst electrical current, and relative light intensity against ambienttemperature.
 9. A controlled light emitting system comprising: a lightemitting module according to claim 1; and, a control system for managingactivation properties of at least one of the first, second, third andfourth light emitting packages in the light emitting module whenactivated, the control system being adapted to manage the activationproperties to achieve a predefined colour chromaticity and CRI for thetotal light emitted by the light emitting module.
 10. A controlled lightemitting system according to claim 9, wherein the control system isfurther adapted to monitor electrical and thermal properties of thelight emitting packages in the module and to provide feedback formodifying activation properties of the light emitting packages in orderto achieve the predefined colour chromaticity and CRI for the totallight emitted by the light emitting module.
 11. A controlled lightemitting system according to claim 9, further comprising a light sensororiented to measure the colour chromaticity properties of at least partof the total light emitted by the light emitting module, the controlsystem being coupled to the light sensor and adapted to provide feedbackto modify activation properties of the light emitting packages toachieve the predefined colour chromaticity and CRI for the total lightemitted by the light emitting module.
 12. A controlled light emittingsystem according to claim 9, wherein the control system further includesan interface for connection to external sources and for receivinginformation from the external sources.
 13. A method of manufacturing thelight emitting unit of claim 7, the method comprising the steps of:providing the first, second and third light emitting packages andattaching them to a sub-mount; affixing a colour mixing element proximalto the submount such that it is at least partially in a propagation pathof the total light emitted by the light emitting module; affixing amemory module proximal to the light emitting module; activating thelight emitting module and determining calibration parameters for themodule; and, registering the calibration parameters on the memorymodule.
 14. A method according to claim 13, the method furthercomprising the steps of: assembling the control system; presettingparameters in the control system; and, interfacing the control system tothe light emitting module and memory module, whereby the control systemis adapted to interrogate the memory module and to employ parametersresiding on the memory for managing the activation properties of atleast one of the first, second, third light emitting package in thelight emitting module to achieve a predefined colour chromaticity andCRI for the total light emitted by the light emitting module.